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A 10,000-mile journey for microbes

Andrea Unzueta-Martinez studied Sydney rock oyster larvae at the Port Stephens Fisheries Institute, located 100 miles northeast of Sydney, Australia. Photo by Rachel Kara for Northeastern University

MELBOURNE, Australia—Andrea Unzueta-Martinez lights up when she talks about the tiny creatures that dominate our lives.

Unzueta-Martinez, a doctoral candidate at Northeastern’s Marine Science Center, spent three months at the Port Stephens Fisheries Institute raising oyster larvae to try and figure out how they acquire their microbiome.

The term refers to the billions of microscopic colonists that inhabit every living creature. Even your own body is teeming with bacteria, viruses, fungi, and archaea—they make up more than half of your cells. 

“They have such a huge impact on the world around them and to animal health,” she said. “I think it’s incredible how much power they have.”

“Like, we are only able to digest our food because of the bacteria in our stomachs—that’s how much we need them.”

Top left and right, Andrea Unzueta-Martinez uses a microscope to observe Sydney rock oyster larvae. Bottom left and right, algae cultures used for daily feeding at the Port Stephens Fisheries Institute. Photos by Rachel Kara for Northeastern University

Unzueta-Martinez’s research examines fundamental questions about where oysters get their microbiome from—the environment or from their parents? In New South Wales, oysters have seen a variety of mass mortality events due to disease and environmental degradation. The industry is keen to see if probiotics can help make oysters more resilient, or if there are other ways to control the microbiome in the larvae so they can better fight disease and grow faster.

The 26-year-old arrived at the institute in January, and lived in a bunkhouse on site, surrounded by bushland on the stunning North Coast of New South Wales, about two and a half hours outside of Sydney. 

The institute is all concrete and industrial noise, dotted with microscopes and filled with plastic tanks to grow sea creatures. One room looks for all the world like a crazed scientist’s laboratory with rows of glass jars, filled with liquid growing algae in a range of colors, bubbling away.

The trip was funded via a National Science Foundation’s Graduate Research Opportunities Worldwide. It’s incredibly competitive to get one, with fewer than 5 percent of applications are successful—and you only get one shot to apply. 

Andrea Unzueta-Martinez stands near the special water filtration system tanks at the Port Stephens Fisheries Institute. Photo by Rachel Kara for Northeastern University

Raising oysters in Australia is a long way from where Unzueta-Martinez saw her future as a young dancer growing up in the Columbian city of Cali. She was spotted by talent scouts for the Boston Ballet, who whisked her and her mother away to a new life on a new continent. “It’s one of the best ballet companies in America and they recruited me into their pre-professional program at the age of 13,” she explained.

Life in Boston was a shock—the harsh winters were in stark contrast to the tropical temperatures of home—and she didn’t speak English.

“It was so different. The language was the biggest barrier, like, having to learn English super-fast. But you know, what doesn’t kill you makes you stronger.”

By the time graduation was in sight, she’d begun to harbor doubts about pursuing a career as a professional dancer. A field trip to Plum Island with her marine biology class in her senior year, suggested an alternative path.

“We would go to the beach and collect animals and see what they were. We learnt the techniques of how people identify different marine life,” she said. “This is a jellyfish, this is some algae. It was really interesting seeing all of that.”

Left, algae cultures used for daily feeding at the Port Stephens Fisheries Institute. Right top and bottom, Andrea Unzueta-Martinez observes adult Sydney rock oysters. Photos by Rachel Kara for Northeastern University

She wrestled with the decision for the best part of 18 months.

“Some people were like: Go to college for dance. But I had just had enough of it. It was my passion for a long time. But when it became this very serious and strict career, I just didn’t love it anymore. It wasn’t fun. It turned something that I loved, into something that was like a job. So, I decided to do something that truly brought me joy and I decided to pursue science.”

It helped that she’d found a marine biology program at the “beautiful” University of Hawaii. “It was Hawaii! It’s like, what could go wrong?” she laughed. She did an internship at a lab researching microbes and bacteria around coral in the ocean and discovered a new passion. “I had no idea that I liked microbiology prior to this internship,” she said.

Yet another internship led her to Jennifer Bowen’s lab at the University of Massachusetts. Bowen, now an associate professor of marine and environmental sciences at Northeastern, remembers being thoroughly impressed with her new intern.

“I just thought she was super sharp and a really enthusiastic self-starter,” she said. “She absolutely wanted to learn everything she could. Everyone in my lab thought she was amazing so that’s why we encouraged her to apply and come work with us.”

Unzueta-Martinez joined Bowen’s lab as a doctoral student when it found its new home at Northeastern’s Marine Science Center. While she could have conducted her research on oysters 10,000 miles closer to home, Bowen believes the international journey was a perfect component for someone on a journey to a PhD. 

“To solve problems on the fly and build the confidence to know that you can figure something out if you need to – there’s no better way to do that than to travel three quarters of the way around the world and plop down in a new environment where you don’t know anybody, and don’t know what you’re doing because you’ve never reared oysters before,” Bowen said. “The confidence you gain from successfully managing that is immeasurable.”

Unzueta-Martinez said the staff at Port Stephens value her expertise in microbial work, while she values their expertise working with larvae. “So that’s how we’re learning from each other,” she said.

The trip has not been without its challenges, however. There is a language barrier, despite the locals ostensibly speaking English: “A lot of people from the hatchery have really, really heavy Australian accents and I have had the hardest time understanding what they’re saying to me – it’s hilarious,” she said. Unzueta-Martinez explained that Aussies tend to shorten words: the afternoon is called the ‘arvo’ and mosquitos are called ‘mozzies’.

She said she was baffled when someone who wanted her to hand them a tool called a homogenizer: They said, “Oh, pass me the homogie. And I’m like ‘the what? I don’t understand?’” She laughs: “‘Mozzie’ took me so long to figure out.”

The research aspect was tough as well, and she faced big problems keeping her oyster larvae alive. She began her experiments with 15 tanks of oyster larvae, and ended with only six.

“Every water change means you lose larvae, and if there’s even a slight change in temperature, or chemistry, pH or salinity, anything could upset them and they just die,” Unzueta-Martinez said. “I had no idea these larvae were so sensitive to everything.”

It’s quite stressful: “It affects my mental health,” she said. However she added that not only did Fisheries staff expect the mortality events, “they have actually been surprised I was able to keep them alive for so long.”

As if these problems weren’t enough of a challenge, Unzueta-Martinez had only just finished her experiments when Northeastern recalled all staff on research or co-op placements around the world due to the spiraling threat from the coronavirus.

What was meant to be a leisurely week visiting the Great Barrier Reef to celebrate a job well done, turned into an anxious race against time to get her DNA samples—and herself—back home, as flights were cancelled and borders slammed shut.

“I didn’t sleep, the whole week was awful,” Unzueta-Martinez said. “I was just pacing around in my room, like ‘Oh my god, oh my god, what’s going to happen?’”

She was terrified she wouldn’t be able to get her samples processed and shipped safely home in time.

“I wouldn’t have graduated,” she said. “It was one chapter for my dissertation and that would have meant my graduation would have been delayed because I would have had to redo it. I basically put all my eggs in one basket.”

The story has a happy ending though: despite having to buy an entirely new flight as her original airline was uncontactable, she made it home safely and her samples did too.

Now back in Boston, Unzueta-Martinez said she’s pleased with how everything turned out and believes she has more than enough data to analyze and draw conclusions from. The main obstacle now, is being granted permission to return to the lab in Nahant, Massachusetts, due to the ongoing social distancing restrictions. Once she gets back in, she estimates it will take a couple of months to process her samples.

“Doing molecular work, extracting DNA, amplifying microbial DNA, purifying—and eventually that will lead to sequencing the data.  And then after sequencing it’s the whole data analysis process …and then I’ll actually be able to look up my data and see what patterns I pick up. It’s a long time until I know my results.”

She estimates the dissertation is still a year or so off, and said she hopes to publish three chapters in peer reviewed journals eventually.

And while she’s found a new passion in the form of microbial science, she’s also rediscovered her love for dancing.

“I usually dance like once a week,” she said. “I’ve joined different dance teams and in the most recent one I was dancing salsa. We’d rehearse once a week and then have some performances. It’s cool. I enjoy it now more as a hobby, rather than having to stress about it as a career.”

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